1. Field
Example embodiments of the present invention relate to a semiconductor memory device, for example, to a data read circuit for increasing the reliability of a read operation in a phase change memory and apparatuses including the same.
2. Description of Related Art
Phase change memory may be formed from a phase change material such as a chalcogenide alloy, which maintains one of two states once cooled after being heated and is changeable between the two states through heating and cooling. The two states are a crystalline state and an amorphous state. The phase change material has a low resistance in the crystalline state and has a high resistance in the amorphous state. The crystalline state is referred to as a “set” state and corresponds to data “0”. The amorphous state is referred to as a “reset” state and corresponds to data “1”.
In a read operation of a phase change memory device, a phase change memory cell to be read is selected from among a plurality of phase change memory cells. When current is supplied to the selected phase change memory cell, a current depending on the resistance of a phase change material is generated. A sense amplifier of a read circuit included in the phase change memory device compares a voltage level changed by the current at a sensing node with a reference voltage level to identify data “0” or data “1”.